C# Closing a Task

Question

I would like to start a task by calling function StartTask() and stop the task by calling the function CloseStream(). The function StartTask() does seem to work but when I try to close it the program only outputs "a1" and is stuck on the "await t" line.

 public class server
 {
           public static string data = null;
           public static TcpClient Socket = new TcpClient();
           public static NetworkStream Stream = default(NetworkStream);
           public static CancellationTokenSource source = new CancellationTokenSource();
           public static bool logging = false;
           public static Task t = new Task(() => TaskAction(),source.Token);
           private static Control textbox;

           public static void StartTask()
           {
               t.Start();
           }
           public static async void CloseTask()
           {
               source.Cancel();
               try
               {
                   Console.WriteLine("a1");
                   await t;
                   Console.WriteLine("a2");
               }
               catch (OperationCanceledException e)
               {
                   Console.WriteLine($"{nameof(OperationCanceledException)} thrown with message: {e.Message}");
               }
               finally
               {
                   source.Dispose();
               }

               Socket.GetStream().Close();
               Socket.Close();
               Socket = new TcpClient();
               Stream = default(NetworkStream);
               Console.WriteLine("closed");

             }

           private static void TaskAction()
           {
                 //so something
           } 

}